Hospitalisation due to respiratory syncytial virus in a population-based cohort of older adults in Spain, 2016/17 to 2019/20

Background Respiratory syncytial virus (RSV) is a major cause of acute respiratory infection that can lead to complications in risk groups. Aim We aimed to estimate the incidence of RSV hospitalisation in adults, determine the risk factors and characterise priority groups for prevention. Methods This population-based cohort study included adults 60 years and older in Navarre, Spain, in seasons 2016/17 to 2019/20. We estimated the rate of RSV hospitalisation confirmed by PCR and evaluated risk factors using Poisson regression. Results Within 642,622 person-years analysed, we detected 544 RSV hospitalisations (average annual rate: 84.7/100,000). The rate varied among seasons between 59.7 and 95.6 per 100,000. The rate ratio of hospitalisation was higher than 3 from the age of 75 years and around 7 in the 85–94 years age group compared with those aged 60–64 years. Nursing home residence, functional dependence, haematological cancer, chronic obstructive pulmonary disease (COPD), asthma, cardiovascular disease, severe obesity, diabetes and chronic kidney disease were independent risk conditions. Rate of RSV hospitalisation was higher than 300 per 100,000 among people with haematological cancer or nursing home residence, those aged ≥ 75 years with COPD or functional dependence, and those aged ≥ 85 years with asthma or cardiovascular disease. These groups represented 13.2% of all adults aged ≥ 60 years and 50.7% of their RSV hospitalisations. On average, these groups had one RSV hospitalisation per 307 person-years. Conclusion Advanced age, in addition to nursing home residence, functional dependence and some comorbidities define priority groups for RSV vaccination.